Not valid for use as an ACS Olympiad Local Section Exam after April 14, 2003. STOCK CODE OL03
2003 U. S. NATIONAL CHEMISTRY OLYMPIAD
LOCAL SECTION EXAM
Prepared by the American Chemical Society Olympiad Examinations Task Force
OLYMPIAD EXAMINATIONS TASK FORCE
Arden P. Zipp, State University of New York, Cortland Chair
Peter E. Demmin (retired), Amherst Central High School, NY David W. Hostage, Taft School, CT
Alice Johnsen, Bellaire High School, TX Jerry D. Mullins, Plano Senior High School, TX
Ronald O. Ragsdale, University of Utah, UT Amy Rogers, College of Charleston, SC
DIRECTIONS TO THE EXAMINER
This test is designed to be taken with an answer sheet on which the student records his or her responses. All answers are to be marked on that sheet, not written in the booklet. Each student should be provided with an answer sheet and scratch paper, both of which must be turned in with the test booklet at the end of the examination. Local Sections may use an answer sheet of their own choice.
The full examination consists of 60 multiple-choice questions representing a fairly wide range of difficulty. Students should be permitted to use non-programmable calculators. A periodic table and other useful information are provided on page two of this exam booklet for student reference.
Suggested Time: 60 questions—110 minutes
DIRECTIONS TO THE EXAMINEE DO NOT TURN THE PAGE UNTIL DIRECTED TO DO SO.
This is a multiple-choice examination with four choices for each question. There is only one correct or best answer to each question.
When you select your choice, blacken the corresponding space on the answer sheet with your pencil. Make a heavy full mark, but no stray marks. If you decide to change your answer, be certain to erase your original answer completely.
ampere A
atmosphere atm
atomic mass unit u
atomic molar mass A Avogadro constant NA
Celsius temperature °C
centi– prefix c
coulomb C
electromotive force E energy of activation Ea
enthalpy H
entropy S
equilibrium constant K
Faraday constant F formula molar mass M
free energy G
frequency ν
gas constant R
gram g
heat capacity Cp
hour h
joule J
kelvin K
kilo– prefix k
liter L
milli– prefix m
molal m
molar M
molar mass M
mole mol
Planck’s constant h
pressure P
rate constant k
retention factor Rf
second s
temperature, K T
time t
volt V
R = 8.314 J·mol–1·K–1 R = 0.0821 L·atm·mol–1·K–1
1 F = 96,500 C·mol–1 1 F = 96,500 J·V–1·mol–1 NA = 6.022 × 1023 mol–1
h = 6.626 × 10–34 J·s c = 2.998 × 108 m·s–1 0 °C = 273.15 K 1 atm = 760 mmHg
EQUATIONS
E E RT nF Q
= o− ln ln K H
R T
= −
+
∆ 1
constant
ln k
k E
R T T
a 2
1 1 2
1 1
= −
1
PERIODIC TABLE OF THE ELEMENTS
181A 8A
1 H
1.008 2 13 14 15 16 17
2A 3A 4A 5A 6A 7A
2 He
4.003
3 Li
6.941
4 Be
9.012
5 B
10.81
6 C
12.01
7 N
14.01
8 O
16.00
9 F
19.00
10 Ne
20.18
11
22.99Na 12
24.31Mg 3 3B
4 4B
5 5B
6 6B
7 7B
8 8B
9 8B
10 8B
11 1B
12 2B
13
26.98Al 14
28.09Si 15
30.97P 16
32.07S 17
35.45Cl 18
39.95Ar 19
K
39.10
20 Ca
40.08
21 Sc
44.96
22 Ti
47.88
23 V
50.94
24 Cr
52.00
25 Mn
54.94
26 Fe
55.85
27 Co
58.93
28 Ni
58.69
29 Cu
63.55
30 Zn
65.39
31 Ga
69.72
32 Ge
72.61
33 As
74.92
34 Se
78.96
35 Br
79.90
36 Kr
83.80
37
85.47Rb 38
87.62Sr 39
88.91Y 40
91.22Zr 41
92.91Nb 42
95.94Mo 43 Tc(98)
44
101.1Ru 45
102.9Rh 46
106.4Pd 47
107.9Ag 48
112.4Cd 49
114.8In 50
118.7Sn 51
121.8Sb 52
127.6Te 53
126.9I 54
131.3Xe 55
Cs
132.9
56 Ba
137.3
57 La
138.9
72 Hf
178.5
73 Ta
180.9
74 W
183.8
75 Re
186.2
76 Os
190.2
77 Ir
192.2
78 Pt
195.1
79 Au
197.0
80 Hg
200.6
81 Tl
204.4
82 Pb
207.2
83 Bi
209.0
84 Po
(209)
85 At
(210)
86 Rn
(222)
87 Fr
(223)
88 Ra
(226)
89 Ac
(227)
104 Rf
(261)
105 Db
(262)
106 Sg
(263)
107 Bh
(262)
108 Hs
(265)
109 Mt
(266)
110
(269)
111
(272)
112
(277)
114
(2??)
58 Ce
140.1
59 Pr
140.9
60 Nd
144.2
61 Pm
(145)
62 Sm
150.4
63 Eu
152.0
64 Gd
157.3
65 Tb
158.9
66 Dy
162.5
67 Ho
164.9
68 Er
167.3
69 Tm
168.9
70 Yb
173.0
71 Lu
175.0
90 Th
232.0
91 Pa
231.0
92 U
238.0
93 Np
(237)
94 Pu
(244)
95 Am
(243)
96 Cm
(247)
97 Bk
(247)
98 Cf
(251)
99 Es
(252)
100 Fm
(257)
101 Md
(258)
102 No
(259)
103 Lr
(262)
DIRECTIONS
! When you have selected your answer to each question, blacken the corresponding space on the answer sheet using a soft, #2 pencil. Make a heavy, full mark, but no stray marks. If you decide to change an answer, erase the unwanted mark very carefully.
! There is only one correct answer to each question. Any questions for which more than one response has been blackened will not be counted.
! Your score is based solely on the number of questions you answer correctly. It is to your advantage to answer every question.
1. Which anion forms the smallest number of insoluble salts?
(A) Cl- (B) NO3- (C) CO3
2- (D) SO4 2-
2. Which piece of apparatus can measure a volume of 25.0 mL most precisely?
(A) 25 mL beaker (B) 25 mL conical flask (C) 25 mL graduated
cylinder
(D) 25 mL pipet
3. How many significant figures should be reported in the answer to the calculation (Assume all numbers are experimentally determined.)
12 501 3 52 0 0042 6 044
. .
. × + .
(A) 2 (B) 3 (C) 4 (D) 5
4. Five pellets of a metal have a total mass of 1.25 g and a total volume of 0.278 mL. What is the density of the metal in g·mL-1?
(A) 0.348 (B) 0.900 (C) 4.50 (D) 22.5 5. What is the color of the flame test for sodium?
(A) green (B) red
(C) violet (D) yellow
6. When is it acceptable to eat in a chemistry laboratory?
(A) Anytime when a person is not doing an experiment.
(B) Whenever there are no hazardous chemicals out.
(C) If it is necessary to do so in order to keep another appointment.
(D) Never.
7. Selenium (Se) is similar to sulfur in its properties and francium (Fr) is an alkali metal. What is the formula for francium selenite?
(A) FrSeO2 (B) Fr2SeO4
(C) Fr2SeO3 (D) Fr2Se2O3
Molar mass, g·mol-1 8. Calculate the mass percentage of
nitrogen in hydrazinium sulfate
(N2H5)2SO4. (N2H5)2SO4 162.2 (A) 10.8 (B) 17.3 (C) 34.5 (D) 51.2 9. How many ozone molecules are in 3.20 g of O3?
(A) 4.0 × 1022 (B) 6.0 × 1022 (C) 1.2 × 1023 (D) 6.0 × 1023 10. Acetylene, C2H2, reacts with oxygen according to the
unbalanced equation:
C2H2 (g) + O2 (g) r CO2 (g) + H2O(g)
What is the O2/C2H2 ratio when this equation is correctly balanced?
(A) 2/1 (B) 3/1 (C) 4/1 (D) 5/2 11. Silicon carbide, SiC, is produced by heating SiO2 and C
to high temperatures according to the equation:
SiO2 (s) + 3C(s) r SiC(s) + 2CO(g)
How many grams of SiC could be formed by reacting 2.00 g of SiO2 and 2.00 g of C?
(A) 1.33 (B) 2.26 (C) 3.59 (D) 4.00 Molar mass, g·mol-1 Na2SO4 142 12. A 7.66 g sample of hydrated
sodium sulfate, Na2SO4.xH2O, forms 4.06 g of anhydrous Na2SO4. What is the value of x?
(A) 0.2 (B) 3.6 (C) 5 (D) 7
13. Silver metal reacts with nitric acid according to the equation:
3Ag(s) + 4HNO3(aq) r
3AgNO3 (aq) + NO(g) + 2H2O(l) What volume of 1.15 M HNO3(aq) is required to react with 0.784 g of silver?
(A) 4.74 mL (B) 6.32 mL
(C) 8.43 mL (D) 25.3 mL
14. Which solute produces the highest boiling point in a 0.15 m aqueous solution?
(A) CaCl2 (B) NaBr (C) CuSO4 (D) CH3OH
What is the volume if the pressure is changed to 0.20 atm at constant temperature?
(A) 1.5 L (B) 3.0 L (C) 12 L (D) 24 L 16. Which will increase the
vapor pressure of a liquid? 1 increase in temperature 2 increase in surface area
(A) 1 only (B) 2 only
(C) Both 1 and 2 (D) Neither 1 nor 2 17. What pressure (in atm) will be exerted by a 1.00 g sample
of methane, CH4, in a 4.25 L flask at 115˚C?
(A) 0.139 (B) 0.330 (C) 0.467 (D) 7.50 18. The lowest melting points overall occur for members of
which class of solids?
(A) ionic (B) metallic
(C) molecular (D) network covalent 19. What are the strongest intermolecular force between
neighboring carbon tetrachloride, CCl4, molecules?
(A) dipole-dipole forces (B) dispersion forces (C) hydrogen bonds (D) covalent bonds 20. According to the phase
diagram shown, where does a mixture of solid and liquid exist at equilibrium?
M N
L K
Temperature
Pressure
(A) along line MN (B) along line KN (C) along line LN (D) in the region KNL
∆∆∆∆Hf˚, (kJ.mol-1) 21. Calculate the amount of energy
released when 0.100 mol of diborane, B2H6, reacts with oxygen to produce solid B2O3
and steam.
B2H6(g) 35
B2O3(s) -1272
H2O(l) -285
H2O(g) -241
(A) 203 kJ (B) 216 kJ (C) 330 kJ (D) 343 kJ Specific heat, J ·g-1·˚C-1 22 How much heat is required to raise the temperature of 100. g of Fe2O3 from 5.0˚C to 25.0˚C? Fe2O3 0.634 (A) 1.58 kJ (B) 1.27 kJ (C) 0.845 kJ (D) 0.0634 kJ Br2(l) + F2(g) r 2BrF(g) Br2(l) + 3F2(g) r 2BrF3(g) determine ∆H˚ for the reaction BrF(g) + F2(g) r BrF3(g) ∆H˚ = -188 kJ ∆H˚ = -768 kJ ∆H˚ = ? (A) -956 kJ (B) -580 kJ (C) -478 kJ (D) -290 kJ Bond Energy, kJ.mol-1 24. Use bond energies to calculate ∆H˚ for the reaction: H2(g) + O2(g) r H2O2(g) H-H 432
H-O 459
O-O 207
O=O 494
(A) -521 kJ (B) -486 kJ
(C) -199 kJ (D) 199 kJ
25. Which reaction occurs with a decrease in entropy?
(A) N2(g) + O2(g) r 2NO(g) (B) N2O4(g) r 2NO2(g) (C) 2CO(g) r C(s) + CO2(g) (D) 2HCl(aq) + Ag2CO3(s) r
2AgCl(s) + CO2(g) + H2O(l) 26. A homogeneous liquid reaction mixture is often heated to
increase the rate of reaction. This is best explained by the fact that raising the temperature
(A) increases the heat of reaction.
(B) decreases the energy of activation.
(C) increases the vapor pressure of the liquid
(D) increases the average kinetic energy of the reactants.
27. For the reaction, 2A + B r C
which relationship is correct?
(A) ∆[A] = ∆[C] (B) -∆[A] = ∆[C]
(C) -2∆[A] = ∆[C] (D) -∆[A] = 2∆[C]
This exothermic reaction is catalyzed by MnO2(s).
2H2O2(aq) r 2H2O(l) + O2(g)
Which of the following will increase the rate of this reaction?
28.
1. Raising the temperature
2. Increasing the surface area of MnO2(s)
(A) 1 only (B) 2 only
(C) Both 1 and 2 (D) Neither 1 and 2
29. Which is constant for different reactant concentrations in a first-order reaction?
(A) The time required for the concentration of reactants to drop below 0.001 M.
(B) The time required for one-half of reactants to disappear.
(C) The rate of disappearance of reactants in mol.L-1 .time-1.
(D) The rate of formation of products in mol.L-1 .time-1. The reaction,
3I-(aq) + S2O8
2-(aq) r I3-(aq) + 2SO4 2–(aq) yields the kinetic data in the table.
[I-]o (mol.L-1) [S2O8
2-]o (mol.L-1) Relative Rate 0.001
0.002 0.002
0.001 0.001 0.002
1 2 4 30.
What is the rate equation?
(A) Rate = k[I-][ S2O8
2-] (B) Rate = k[I-]2[S2O8 2-] (C) Rate = k[I-]3[S2O8
2-] (D) Rate = k[I-]2[S2O8 2-]2 31. For the reaction,
2CCl4(g) + O2(g) s 2COCl2(g) + 2Cl2(g) what is the equilibrium expression, Kc?
(A) Kc=
[
COCl][ ]
Cl[CCl ][O ]
2 2
4 2
(B) Kc =2 COCl
[ ][ ]
Cl[CCl ][O ]
2 2
4 2
(C)
Kc =
[
COCl][ ]
Cl[CCl ][O ]
2 2
4 2
2 (D)
Kc=
[
COCl] [ ]
Cl[CCl ] [O ]
2 2
4 2
2
2 2
For the reaction,
2SO2(g) + O2(g) s 2SO3(g) ∆H˚ < 0 Which change(s) will increase the fraction of SO3(g) in the equilibrium mixture?
32.
1. Increasing the pressure 2. Increasing the temperature 3. Adding a catalyst
(A) 1 only (B) 3 only
(C) 1 and 3 only (D) 1, 2 and 3 33. What is the [H+] in a 0.10 M Ka
solution of ascorbic acid,
C6H8O6? C6H8O6 8.0 × 10-5 (A) 8.0 × 10-6 M (B) 2.8 × 10-3 M (C) 4.0 × 10-3 M (D) 5.3 × 10-3 M
34. A 0.10 M solution of which salt is the most acidic?
(A) NH4C2H3O2 (B) NaCN
(C) KNO3 (D) AlCl3
35. A student is asked to prepare a Ka buffer solution with a pH of 4.00. This can be accomplished by using a solution containing which of the following?
HNO2 4.5 × 10-4 HCN 4.9 × 10-10
(A) HNO2 only (B) HCN only (C) HNO2 and NaNO2 (D) HCN and NaCN 36. A saturated solution of Ksp
which compound has the
lowest [Ca2+]? CaF2 4.0 × 10-11 CaCO3 8.7 × 10-9 Ca(OH)2 8.0 × 10-6 CaSO4 2.4 × 10-5 (A) CaF2 (B) CaCO3 (C) Ca(OH)2 (D) CaSO4
37. Which reaction occurs at the cathode during the electrolysis of an aqueous solution of KCl?
(A) K+(aq) + e- r K(s)
(B) 2 H2O(l) + 2e- r H2(g) + 2OH-(aq) (C) 2Cl-(aq) r Cl2(g) + 2e-
(D) 2H2O(l) r O2(g) + 4H+(aq) + 4e-
Correct statements about a voltaic (galvanic) cell include which of the following?
38.
1. Oxidation occurs at the anode.
2. Electrons flow from the cathode to the anode.
(A) 1 only (B) 2 only
(C) Both 1 and 2 (D) Neither 1 nor 2 39. MnO4- + NO2- + H+ r Mn2+ + NO3- + H2O
When this equation is balanced correctly with the smallest integer coefficients, what is the coefficient for H+?
(A) 1 (B) 6 (C) 8 (D) 16
40. An electrochemical cell constructed for the reaction:
Cu2+(aq) + M(s) r Cu(s) + M2+(aq)
has an E˚ = 0.75 V. The standard reduction potential for Cu2+(aq) is 0.34 V. What is the standard reduction potential for M2+(aq)?
(A) 1.09 V (B) 0.410 V
(C) -0.410 V (D) -1.09 V
(A) CrO3 r CrOF3 (B) Cr3+ r Cr(OH)4- (C) 2CrO42- r Cr2O7
2- (D) Cr3+ r CrO4 2-
42. 1.0 M aqueous solutions of AgNO3, Cu(NO3)2 and Au(NO3) 3 are electrolyzed in the apparatus shown, so the same amount of electricity passes through each solution. If 0.10 moles of solid Cu are formed how many moles of Ag and Au are formed?
Ag+ Cu2+ Au3+
(A) 0.10 moles Ag, 0.10 moles Au (B) 0.05 moles Ag, 0.075 moles Au (C) 0.05 moles Ag, 0.15 moles Au (D) 0.20 moles Ag, 0.067 moles Au
43. In a hydrogen atom, which transition produces a photon with the highest energy?
(A) n = 3 r n = 1 (B) n = 5 r n = 3 (C) n = 12 r n = 10 (D) n = 22 r n = 20 44. How many orbitals in a ground state oxygen atom are
completely filled?
(A) 1 (B) 2 (C) 3 (D) 4
45. Which atom has the smallest first ionization energy?
(A) Na (B) K (C) Mg (D) Ca
46. The electron configuration of a cobalt atom is 1s22s22p63s23p63d74s2.
How many unpaired electrons are present in a gaseous Co3+ ion in its ground state?
(A) 6 (B) 4 (C) 2 (D) 0
47. When the atoms; P (Z = 15), S (Z = 16) and As (Z = 33), are arranged in order of increasing radius, what is the correct order?
(A) P, S, As (B) As, S, P (C) S, P, As (D) P, As, S 48. The oxide of which element is the most ionic?
(A) Al (B) B (C) C (D) Si
49. All of the following lists include at least one ionic compound EXCEPT
(A) NO2, NaNO2, KNO3 (B) CF4, CaF2, HF (C) NaCl, MgCl2, SCl2 (D) H2S, SO2, SF6
50. Which species below has the same general shape as NH3? (A) SO3
2- (B) CO3
2- (C) NO3- (D) SO3
51. When forming covalent bonds, which atom can have more than eight valence electrons?
(A) H (B) N (C) F (D) Cl
52. Which diatomic molecule has the shortest bond length?
(A) N2 (B) O2 (C) F2 (D) S2
53. Which species is nonpolar?
(A) HCl (B) OCl2 (C) NCl3 (D) CCl4
54. In which species are all the carbon atoms considered to be sp2 hybridized?
(A) C2H2 (B) C2H4 (C) C3H8 (D) C4H10
55. Which formula can be used to represent an alkynes?
(A) CnH2n-2 (B) CnH2n
(C) CnH2n+2 (D) CnH2n+4
56. How many different structural isomers exist for dichloropropane, C3H6Cl2?
(A) 4 (B) 5 (C) 6
(D) some other number
57. All of the formulas below correspond to stable compounds EXCEPT
(A) CH2O (B) CH2O2
(C) CH3O (D) CH4O
58. Which of the compounds shown are isomers?
1 CH3CH2OCH3
2 CH3CH2OCH2CH3
3 CH3CH2CH2OH 4 CH2=CHOCH3
(A) 1 and 3 (B) 1 and 2
(C) 2 and 3 (D) 1 and 4
59. Which functional group is present in CH3COOH?
(A) aldehyde (B) carboxylic acid (C) alcohol (D) hydroperoxide 60. How many sigma bonds does a molecule of ethene have?
(A) 1 (B) 4 (C) 5 (D) 7
